Systematic review with meta-analysis of the epidemiological evidence in the 1900s relating smoking to lung cancer

Lee, Peter N; Forey, Barbara A; Coombs, Katharine J

doi:10.1186/1471-2407-12-385

BMC Cancer

Table 10 Meta-regression analyses for current smoking of any product (or cigarettes if any product not available) ^a

From: Systematic review with meta-analysis of the epidemiological evidence in the 1900s relating smoking to lung cancer

Characteristic	Level	All lung cancer		Squamous		Adeno
		Estimate^b(SE^c)	p^d	Estimate^b(SE^c)	p^d	Estimate^b(SE^c)	p^d
Constant		+1.566 (0.081)		+1.193 (0.239)		+0.816 (0.239)
Sex	Male	Base	<0.01	Base	NS	Base	<0.001
	Female	−0.204 (0.029)		−0.002 (0.088)		−0.440 (0.067)
	Combined	−0.043 (0.039)		+0.224 (0.459)		−0.612 (0.378)
Location	North America	Base	<0.001	Base	<0.05	Base	<0.001
	United Kingdom	−0.345 (0.071)		No data		No data
	Scandinavia	−0.417 (0.066)		−0.177 (0.513)		−0.298 (0.320)
	Other Europe	−0.602 (0.057)		−0.440 (0.266)		−1.157 (0.178)
	China	−1.528 (0.097)		No data		No data
	Japan	−1.174 (0.056)		−1.174 (0.193)		−1.525 (0.136)
	Other Asia	−1.221 (0.139)		No data		No data
	Other or multiregion	−0.593 (0.088)		−1.221 (1.045)		−1.014 (0.754)
Start year of study	Before 1960	Base	<0.001	Base	<0.1	Base	<0.05
	1960-69	+0.538 (0.063)		+1.374 (0.321)		+1.179 (0.231)
	1970-79	+0.571 (0.058)		+0.896 (0.418)		+1.142 (0.258)
	1980-89	+0.788 (0.051)		+1.276 (0.325)		+0.957 (0.224)
	1990 or later	+1.169 (0.089)		+2.817 (0.823)		+1.982 (0.575)
Study type	Case–control	Base	<0.1	Base	NS	Base	NS
	Prospective^e	+0.182 (0.047)		+0.404 (0.371)		+0.178 (0.224)
Number of cases^f	100-249	Base	<0.1	Base	NS	Base	NS
	250-499	+0.222 (0.071)		+0.420 (0.384)		−0.002 (0.195)
	500-999	+0.266 (0.070)		+0.852 (0.400)		+0.646 (0.232)
	1000+	+0.340 (0.062)		+0.803 (0.298)		+0.362 (0.149)
Number of adjustment factors	0	Base	NS	Base	<0.05	Base	NS
	1	+0.002 (0.047)		+0.428 (0.277)		+0.195 (0.213)
	2+	+0.069 (0.034)		−0.447 (0.175)		+0.283 (0.125)

^a Based on the same data as for Table 8. See that table for further definition of RRs selected for analysis, and numbers of estimates of each characteristic level.
^b Estimates are of log RR. The predicted RR of a given estimate can be calculated by adding the constant to the values for the level of each characteristic applicable to the estimate (taking the value for a base level as zero) and taking the exponential of the result.
^c SE = standard error.
^d The p value is estimated from the drop in deviance from removing the characteristic from the fixed model using an F-test. It is expressed as p < 0.001, p < 0.01, p < 0.05, p < 0.1 or NS (p ≥ 0.1).
^e Or nested case–control or case-cohort in the case of 5 estimates for all lung cancer, 3 for squamous and 3 for adeno.
^f In the study as a whole.
Note For the forward stepwise analyses, deviances, degrees of freedom and p values for inclusion in order of inclusion are as follows:
All lung cancer: Constant 2669.216 on 194 d.f. (p < 0.001), location 1257.714 on 187 d.f. (p < 0.001), start year of study 918.536 on 183 d.f. (p < 0.001) and sex 869.479 on 181 d.f. (p < 0.01). Fixed model deviance 819.856 on 175 d.f.
Squamous: Constant 288.688 on 40 d.f. (p < 0.001), location 194.753 on 36 d.f. (p < 0.01), start year of study 143.741 on 32 d.f. (p < 0.05) and number of adjustment variables 100.916 on 30 d.f. (p < 0.01). Fixed model deviance 86.049 on 24 d.f.
Adeno: Constant 528.128 on 43 d.f. (p < 0.001), location 170.181 on 39 d.f. (p < 0.001), sex 128.397 on 37 d.f. (p < 0.01) and start year of study 89.243 on 33 d.f. (p < 0.05). Fixed model deviance 65.727 on 27 d.f.

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